Non-Lethal Electric Chair Brings the Death Row Experience Home

Non-Lethal electric chair for Oculus Rift Hackathon

One of our trusty tipsters named [Arman] wrote in to tell us about this awesome little Horror VR Hackathon that sought to create a non-lethal electric chair, for a seriously creepy and shocking experience.

[Arman] works in a small prototyping shop, so when a few guys from the local VR group called to ask for help building a non-lethal electric chair, he thought they were joking — until they showed up at the shop! Finally understanding what they really wanted to do, he hooked them up with an EL wire power supply (high voltage AC, low amperage) for their first prototype.

Unfortunately the EL power supply driver took too much juice, so they called [Arman] back the next day to hack together some of those joke gum shockers instead — he hooked them up to an Arduino and they work like a charm.  [Read more...]

In-N-Out Boards Sans Hamburgers

board Before this project, [David]‘s office had a fairly terrible system to tell everyone who was in the office, who was out, and who wasn’t coming in today. Velcro and whiteboards will do the job, but arcade buttons and LEDs called to [David], leading him to create this In/Out Status Board.

The old system consisted of a whiteboard on the side of each partition, with velcroed labels indicating if a particular person was in the office today, out, sick, or on holiday. Inconvenient to change, and there was no single place everyone could look to see if a particular person was in or not. The new system consists of a four-person pod with four arcade buttons and WS2811 LEDs, an Arduino Nano, and a 433 MHz radio. The main panel is just a bigger version of the four-person pod, keeping track of everyone in the office.

A single button switch will change a person from being in to being out, with longer presses necessary for ‘sick’ and ‘vacation’. It’s interesting to note what’s not included in this build: A fingerprint scanner was out of the question, because that would effectively eliminate anyone ever being marked as ‘sick’. An RFID tag reader was out for the same reason. Also not included is a display. That’s just fine, really – [David] won’t be changing the labels very often, anyway, and that would just add to the cost and complexity of the project.

Door Lock Provides Peace of Mind With Real-Time Security

arduino door lock

[HSP] got tired of locking his door with a key, so he decided to upgrade to a keypad system which he’s designed himself.

It uses an Arduino Mega with the standard 44780 display, a standard keypad, and the “key override” (shown above) for fun. The locking mechanism is a standard 12V actuator based lock which was modified to run off of only 7.5V, by softening up the spring inside and running it upside down (as to let gravity help do the work). The whole system draws less than half a watt on standby, and engaging the lock peaks at only 4-7W.

What’s really clever about this design is how he locks it from inside the room. He’s programmed the Arduino to write 1 to address 128 of the EEPROM — at power on it will increment this by 1, and after 5 seconds, it will reset to 1. This means it can detect a quick power cycle, so you can lock the door by turning it off, turning it on for a few seconds, and turning it off and on again — he did this so he didn’t have to make a button or console, or any kind of wireless control on the inside. [Read more...]

Lego Drawing Machine Draws Block Shapes Best

Lego-drawing machine

Loving to draw but deathly afraid of pen ink, [Marcel] came up with a little drawing machine made out of Lego that will do it for him. It’s not a very complicated build but it does have several different components arranged such to complete a task, and that in itself is cool. Oh yeah, just kidding about the “afraid of pen ink” thing.

RC Car Servos are used to drive the pen in the X and Y directions. These servos only have a 180 degree range of motion which is not enough to move the pen very far. To increase the pen’s travel distance, [Marcel] attached a large gear to the servo which rotates a much smaller gear that rides on a rack gear attached to the bed. A Lego hinge takes the place of a Z axis and is used to set the height of the pen that is strapped to the machine via rubber band.

In order to make the machine draw, the user moves an analog joystick. The changing resistance values of the joystick’s potentiometers are measured by an Arduino. The Arduino then moves each servo to the appropriate position using PWM. If you’d like to know how to do this, check out the Knob Tutorial.

If you’re not ready to l’eggo your Lego drawing machines, check out this super complicated creation or this arm emulator that draws the Mona Lisa.


A Simple Commodore 64 Cart Dumper


While [Rob] was digging around in his garage one day, he ran across an old Commodore 64 cartridge. With no ROM to be found online, he started wondering what was stored in this ancient device. Taking a peek at the bits stored in this cartridge would require dumping the entire thing to a modern computer, and armed with an Arduino, he created a simple cart dumper, capable of reading standard 8k cartridges without issue.

The expansion port for the C64 has a lot of pins corresponding to the control logic inside these old computers, but the only ones [Rob] were really interested in were the eight data lines and the sixteen address lines. With a little bit of code, [Rob] got an Arduino Mega to step through all the address pins and read the corresponding data at that location in memory. This data is then sent over USB to a C app that dumps everything in HEX and text.

While the ROM for just about every C64 game can be found online, [Rob] was unlucky enough to find one that wasn’t. It doesn’t really matter, though, as we don’t know if [Rob] has the 1541 disk drive that makes this cart useful. Still, it’s a good reminder of how useful an Arduino can be when used as an electronic swiss army knife.

Upgraded Nerf Gun Keeps Track of your Ammo


[Paul] and his buddy [Jonathan] recently had a zombie themed Larp event to go to, so in the spirit of making the experience more realistic, they decided to upgrade their Nerf N-Strike Stryfe gun.

They started by cracking open the gun and making note of the available space for a few bells and whistles. Luckily, thanks to traditional plastic injection molding practices — there’s lots of room!

Upgrades include a magazine sensor, a jam sensor, a trigger sensor and a voltmeter to make the gun a little bit smarter. A knockoff Arduino Pro Mini takes in all these inputs and outputs it to a 7-segment LED display for easy visibility. Our favorite part is the ammo sensor, which keeps a tally of how many shots you’ve used. It’s simply an IR photo-diode and IR transistor in a Darlington configuration, connected to the GPIO interrupt pin on the fake Arduino.

[Read more...]

Visualize Vroom with This RGB LED Tachometer

tach[Pete Mills] recently bought the all-new Ford Fiesta, which offers impressive fuel economy over that of his Jeep. He soon figured out that he has real time access to a wealth of engine and chassis data through Ford’s OpenXC platform and used it to build blueShift, a neopixel tachometer. The car already has a tach, but this one is more visual, can be seen in periphery, and is just plain fun.

In case you hadn’t heard, the OpenXC platform is Ford’s consumer key to the kingdom of OBD2 treasures. It unlocks the magic through its Vehicle Interface, which plugs into the OBD2 port and translates the CAN bus messages to OpenXC format. These messages are packaged into JSON format and can be sent over Bluetooth or Ethernet/Wi-Fi to an Android, Python, or iOS device.

[Pete] went with Bluetooth and used a BlueSMiRF with an Arduino Pro Mini. He derives power from the car’s on-board USB port, but has future plans to use the OpenXC VI port. blueShift reads the RPM data and displays a green trail as the engine revs up. At the peak revolution, it shows a red LED. This one is sticky and will persist for the lesser of three seconds or the time elapsed to a new positive RPM. [Pete] is also reading the headlight status of the car. As soon as they come on, the RGB LEDs dim to avoid blinding him at night.

[Pete] wanted to make an enclosure more finished-looking than a Tupperware box. He nearly detoured into 3D-printer design, but ended up putting together a Prusa i3v and came up with this RAM mount-compatible enclosure. His fantastic write-up and code are on his blog, but you can make the jump to see a short demo and a full explanation video. You can also make smart brake lights or even create art with OpenXC.

[Read more...]


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